COLLAPSE SIMULATION OF AMMU HAWU TRADITIONAL TIMBER HOUSE

Cindy Novaria Nada K, Ali Awaludin, ST., M.Eng., Ph.D.

2014 | Tesis | S2 Teknik Sipil

Sebagian besar wilayah Indonesia terekspos dengan resiko gempa gempa skala besar, akan tetapi banyak rumah-rumah tradisional kayu masih tetap berdiri terhadap gempa. Salah satu rumah tradisional kayu Indonesia yakni Omo Hada, rumah adat Nias selamat tanpa kerusakan struktural setelah gempa Sumatra Utara 8,6 SR.. Di Jepang, banyak perumahan telah dibangun menggunakan material kayu dalam rangka untuk menghindari terjadinya keruntuhan ketika gempa besar berlangsung. Kayu dianggap sebagai bahan konstruksi yang memiliki peran penting dan dapat diandalkan dalam hal ini, karena bahannya yang terbaharukan dan juga memiliki berat jenis yang ringan dikarenakan karakteristik materialnya sendiri. Mekanisme keruntuhan rumah tradisional Ammu Hawu dengan kayu Lontar (Borassus flabellifer) sebagai material utama dianalisis menggunakan software Wallstat dan Extended Distinct Element Method sebagai teori dasarnya. Wallstat adalah program analisis keruntuhan yang sudah dipergunakan oleh penelitian-penelitian sebelumnya untuk memodelkan keruntuhan suatu bangunan selama waktu gempa. Dalam penelitian ini, sepuluh model dianalisis terhadap gempa El Centro 1940, gempa Kobe 1995 dan gempa El Centro 1940 modifikasi ¸ yakni Model 0, 1, 2, 3, 4, 5 sampai 11. Model 0 adalah model dengan tanpa perkuatan apapun. Pada Model 1, 2, 3, 4 dan 5 diperkuat dengan dinding geser vertikal pada lantai dua. Model 6, 7, 8 dan 9 diperkuat dengan pengaku bracing pada kolom-kolom lantai pertama, Sedangkan pada Model 10 adalahModel 5 yang dikenakan gempa El Centro modifikasi. Model-model dengan perkuatan dinding geser pada lantai dua runtuh dan didapati terjadi soft story akibat gempa El Centro dan Kobe. Didapati jiga nilai gaya geser dasar pada Model 3 sampai 5 lebih besar dibandingkan model aslinya, yakni Model 0. Sedangkan, Model 6 sampai Model 9 selamat dan gaya geser dasar nya juga lebih kecil dibandingkan model asli. Sistem perkuatan bracing ini menunjukkan keefektifannya dalam menahan gempa dan gaya geser ke kesuluruhan struktur. Soft story tidak terjadi dalam model-model ini. Dari semua parameter tersebut, dapat disimpulkan bahwa perkuatan bracing pada lantai satu lebih efektif dalam menahan struktur dari keruntuhan terhadap gempa dibandingkan dengan penambahan dinding geser vertikal pada lantai dua. Kata-kata Kunci: Rumah tradisional Ammu Hawu, Borassus flabellifer, software Wallstat, Extended Distinct Element Method (EDEM), Dinding geser vertikal, Bracing, Mekanisme keruntuhan.

Most parts of Indonesia are quite exposed to the risk of major earthquakes, but many traditional timber houses were survived due to earthquake. One of Indonesian traditional timber house is Omo Hada, an indigenous house of Nias people was survived with no damage after the Mw 8.6 Northern Sumatra Earthquake. In Japan, many residential building has been built by using wood material in order to prevent collapse during major earthquake. Wood is considered as one of the most important and reliable construction materials, since it is a renewable and has low weight due to its properties. Collapse mechanism of Ammu Hawu Traditional House with Palm wood (Borassus flabellifer) as main material was analyzed by using Wallstat software and Extended Distinct Element Method (EDEM) as the basis theory. Wallstat is a collapse analysis program which already used in many previous researches to simulate collapse during times of seismic motion. In this study, there are ten models that were analyzed due to El Centro Earthquake 1940, Kobe Earthquake 1995 and Modified El Centro Earthquake 1940, those are, Model 0, 1, 2, 3, 4, 5 up to 11. Model 0 is original model with no reinforcement. In the Model 1, 2, 3, 4, and 5 are the models reinforced with additional vertical shear wall at second story. Model 6, 7, 8, and 9 are the models reinforced with bracing at the first story columns. Whereas in Model 10 is Model 5 which are subjected to modified El Centro Earthquake 1940. The models reinforced with vertical shear walls at second story collapsed and it was found that soft-story occurred due to the El Centro and Kobe Earthquake. It was also found that base shear force values in Model 3 through 5 are higher than the original model, that is, Model 0. Otherwise, Model 6 through 9 survived and the base shear force are smaller than that of Model 0. This bracing reinforcement system showed the effectiveness in preventing earthquake and base shear force to whole structure. Soft-story did not occur in these models. Model 10 also survived due to modified El Centro earthquake. It indicates that the still survive due to local scale earthquake. Moreover, internal force values in all models are higher than the original model. From all those aforementioned parameters, it can be concluded that bracing reinforcement at first story is more effective in preventing structure from collapsing due to earthquake than the models with additional vertical shear walls at second story. Keywords: Ammu Hawu traditional house, Borassus flabellifer, Wallstat software, Extended Distinct Element Method (EDEM), Vertical shear wall, Brace, Collapse mechanism.

Kata Kunci : Rumah tradisional Ammu Hawu, Borassus flabellifer, software Wallstat, Extended Distinct Element Method (EDEM), Dinding geser vertikal, Bracing, Mekanisme keruntuhan.